// 背景图片
bg-image($url)
  background-image: url($url + "@2x.png");
  @media (-webkit-min-device-pixel-ratio: 3), (min-device-pixel-ratio: 3)
    background-image: url($url + "@3x.png");

// 不换行
no-wrap()
  text-overflow: ellipsis;
  overflow: hidden;
  white-space: nowrap;

// 扩展点击区域
extend-click()
  position: relative;
  &:before
    content: "";
    position: absolute;
    top: -10px;
    right: -10px;
    bottom: -10px;
    left: -10px;

